North Korea's highest court has sentenced a South Korea-born Canadian pastor to hard labor for life for subversion, the North's official KCNA news agency reported on Wednesday, a punishment Canada condemned as "unduly harsh."

Hyeon Soo Lim, the head pastor at one of Canada's largest churches, has been held by North Korea since February and has appeared on its state media confessing to crimes against the state. He had been doing humanitarian work in North Korea since 1997, according to his church.

Lim admitted during the trial to "not only viciously defaming the highest dignity of Korea and its system but also possessing the wicked intention of trying to topple the Republic by staging an anti-state conspiracy," KCNA said.

The court said Lim had attempted to overthrow the North Korean government and undermine its social system with "religious activities" for the past 18 years, China's official Xinhua news agency reported.

The prosecution sought the death penalty, but the defense asked for leniency despite the gravity of his crimes.

The court sentenced him to hard labor for life, KCNA said.

In Ottawa, Prime Minister Justin Trudeau said Canadian officials would continue to press for access to Lim.

"The issues of North Korea's governance and judicial system are well known. We are very concerned about someone being sentenced to life in North Korea," he told reporters.

KCNA did not specify what activities Lim engaged in, but Xinhua reported that Lim confessed to helping people defect from North Korea and had met the U.S. ambassador to Mongolia regarding the plans.

Most defectors fleeing isolated, repressive North Korea travel to South Korea via China and Southeast Asia. It is also possible to defect via Mongolia.

A Canadian source familiar with the file said there was no reason to believe any of the allegations were true, with the trial clearly scripted. The source dismissed the idea Lim had been plotting with the U.S. envoy to Mongolia.

"Is it possible that Pastor Lim crossed paths with the small diplomatic community and the American ambassador while he was in Ulan Baator at some point on his numerous travels to the country? Maybe. Would it be unusual? No," said the source.

A spokeswoman for Lim's church, the 3,000-member Light Korean Presbyterian Church, said that while Lim has been to Mongolia, "he did not meet with any official there."

"The capitulation on that issue at the previous press conference in the DPRK, therefore, was curious," church spokeswoman Lisa Pak said in an email.

HANDS CLASPED

North Korea had previously sentenced Korean-American missionary Kenneth Bae to 15 years of hard labor but released him last year after holding him for two years.

Lim's church has said Lim had visited the North more than 100 times since 1997 and helped set up an orphanage and a nursing home.

Lim, who has lived in Canada since 1986 and is a Canadian citizen, has a "very serious health problem, very high blood pressure," his church said. He was 60 at the time of capture.

He is the only Western citizen known to be held currently in North Korea.

Both North Korea and neighboring China have clamped down on Christian groups in recent years.

Last year, Pyongyang released three detained Americans, including Bae and another man who had left a copy of the Bible at a club. It freed a South Korean national with a U.S. green card in October this year after holding him for six months.

In June, the North's highest court sentenced two South Koreans accused of spying for Seoul to hard labor for life. The pair are among three South Koreans known to be held by the North.